Which gas makes up four-fifths of the air in our atmosphere?

The correct answer is nitrogen, as it constitutes approximately 78% of the Earth's atmosphere, making it the most abundant gas present. Its prevalence plays a crucial role in atmospheric composition and processes, as nitrogen is inert and does not readily react with other substances, which helps maintain the stability of the atmosphere. While we often consider oxygen and other gases in relation to life and combustion, nitrogen's significant presence is vital in diluting oxygen, preventing fires from being too intense and ensuring a healthy balance for living organisms. Understanding the role of nitrogen in the atmosphere is essential for grasping broader concepts in environmental science and air quality.